Oxidant-Accelerated Polymerization of Dopamine for Coating DNAN with Enhanced Toughness

Due to the significantly reduced toxicity and shock sensitivity compared to TNT, DNAN is getting more and more attention in the study of insensitive munitions. However, the brittleness problem of DNAN limits its wide application. Inspired by mussels, DNAN particles with a thin and uniform coating based on the self-polymerization of dopamine were prepared by an oxidant-accelerated method in this work. XRD patterns indicated that the DNAN polymorph did not change during the coating process. FT-IR and XPS spectra manifested that the PDA was successfully distributed on the crystal surface. The results of TG-DSC analysis demonstrated that the mass ratio of PDA coating was as low as 1.71%. Meanwhile, Brazilian disk splitting test showed that the tensile strength, tensile strain, and fracture energy of DNAN@PDA cylinder were 16.1%, 32.0% and 53.0% higher than those of pure DNAN cylinder, respectively. The morphology of fracture surface after tensile test indicated that toughness fracture occurred in DNAN@PDA cylinder, while remarkable brittle fracture occurred in pure DNAN cylinder. The surface modification method could enhance the toughness of DNANbased explosives, and the fast fabrication of DNAN@PDA particles on a large scale could satisfy the application demands of insensitive munitions.